US 2988139 A
Description (OCR text may contain errors)
June 13, 1961 Filed Apr-11 50, 1957 H. coANDA 2,988,139
SPRAYING DEVICE 2 Sheets-Sheet 1 eb W In N n q' N d d a N :u gl' w June 13, 1961 HA coANDA SPRAYING DEVICE 2 Sheets-Sheet 2 Filed April 50, 1957 Filed Apr. 30, 1957, Ser. No. 656,025 Claims priority, application France Nov. 14, 1956 3 Claims. (Cl. 158-28) The present invention relates to an improved spraying device having many useful purposes; in particular, it enables the dust content of the atmosphere to be reduced, eliminates smoke and other particles in suspension, climatises air or produces a line spray of a liquid fuel in a combustion supporting gas, etc.
In the U.S. Patent No. 2,720, 425 issued October l1, 1955, to Henri Coanda, there has been described a powdering and spraying device which enables a powder or an atomised liquid to be distributed by means of compressed air, through the use of a set of convergent-divergent nozzles of the Venturi type, each comprising an annular slot arranged so as to permit of the application of the physical phenomenon generally known as the Coanda effect.
The Coanda effect described for example in U.S. Patent No. 2,052,869 issued September l, 1936, to Henri Coanda, is produced when a mass of an elastic fluid, and in particular a gas, is discharged from a chamber in which it is present under pressure, through a slot. The slot has an extended lip which continually recedes, either in a continuously progressive or stepped manner, from the direction of emergence of the gas from the slot; due to the Coanda effect, the outlet gas creates a pressure drop and draws-in a supplementary mass of ambient liuid which is therefore set into motion.
ln the case of a convergent-divergent discharge nozzle of the Venturi type provided in its convergent portion with an annular slot supplied with air under pressure, and the slot has an extended lip which continually recedes in a continuously progressive or stepped manner, from the direction of emergence of said compressed air from said slot (in a radial plane), as described and shown in the above-mentioned U.S. Patent No. 2,720,425 referred to above, the Coanda effect ensures the setting in motion of the fluid which is located on the upstream side of the convergent portion of the discharge nozzle. This supplementary fluid carries with it in Patent 2,720, 425 the fluid to be sprayed or the powder which is to be projected.
In the forms of embodiment described and shown in the Patent 2,720,425, two convergent-divergent annular discharge nozzles are arranged in series, each comprising in its convergent portion an annular slot, the first nozzle in the direction of flow of the uids draws in the liquid or the powder to be distributed, made into a state of fine division by mechanical means, and its divergent portion is adapted to discharge into the convergent portion of the second discharge nozzle, from the divergent portion of which is discharged the jet of powder or liquid to be distributed.
The present invention relates to a spraying device of the same type than that which formed the object of Patent 2,720,425, but in the device according to the present invention, a single convergent-divergent discharge nozzle is provided, having an annular slot for the application of the Coanda effect, and formed in the convergent portion of this nozzle. The liquid to be sprayed is brought in through an injector or jet-nozzle in the immediate vicinity of the said slot, thereby ensuring by the application of the Coanda effect the setting in motion and carrying away of a supplementary quantity of ambient air and finely-divided liquid. An extremely intimate mixture of air and niteci States Patent ICC very finely-divided liquid is thus discharged through the divergent portion of the discharge-nozzle.
There can be thus sprayed or atomized, for the purpose of removing dust, either pure water or water containing a surface active or wetting liquid (as a quaternary ammonium compound, an aryl alkyl sulfonate, or sulfated alcohol etc.) which facilitates the precipitation of the dust, smoke or other particles in suspension in the air to be purified. There is obtained at the outlet of the divergent, an aerosol or an extremely ne mist containing very fine particles of liquid, which ensure an excellent precipitation of the various kinds of dust and smoke contained in the air. It is thus possible to reduce the content of harmful particles in the atmosphere of mines to an acceptable value.
It is in fact well-known that silicosis is a. disease caused among miners by the absorption into the lungs of ne particles of silica caused by the boring of sterile rocks, during the excavation of tunnels through such rocks. These fine particles of silica give rise to lesions in the lungs of the miners and, in spite of the various methods applied to reduce the content of particles of silica in the atmosphere of underground workings, it has still not been possible to overcome this disease, due to the neness of the silica particles, because all known methods remove only the more coarse particles.
Similar problems of dust removal are encountered in other industries, for example in certain chemical industries and in the cement industry.
The present invention provides a radical solution to the problem of dust removal in underground workings, work-shops, mines, etc., by enabling the dust content to be reduced to a very small value by means of the projection of very fine particles of liquid which ensure the precipitation of the dust without giving any trouble to the workmen or miners, the effective protection of whom is ensured against silicosis, and other similar occupational diseases.
It is another object of the present invention to enable the content of smoke to be reduced in work-shops of all kinds by precipitation of the smoke.
Tests carried out with the device according to the invention in the Bruay mine in France have proved that the device enables the content of particles in rock-mining workings to be reduced to a value less than the content of particles at the surface in the neighbouring town of Douai (France). l
The device in accordance with the invention comprises essentially a convergent-divergent discharge-nozzle of the Venturi type, a chamber (preferably arranged around the discharge-nozzle) supplied with a gas under pressure such as compressed air, through a piping system. The gas under pressure is discharged from the chamber through an annular slot formed in the convergent portion of the discharge-nozzle, one lip of the mouth of the slot continually recedes (in a radial plane) from the outlet axis of the said slot (in said plane). An injector supplied with liquid to be distributed is located so as to discharge in the immediate vicinity of the said slot. The liquid is drawn-in with a mass of supplementary air in said convergent portion by the air under pressure passing out of the slot, while the mixture of air and very finelydivided particles of liquid in the discharge nozzle is discharged from the extremity of said nozzle.
The spraying device in accordance with the invention may also be applied to other uses. It can be employed to produce air-conditioning.
It is also an object of the invention to provide a spraying device producing an atomisation of a fuel with a view to ensuring an excellent combustion, and in this case an ignition device is provided at the extremity of the divergent portion, consisting, for example of an electric spark t plug of the kind used in internal combustion engines, with a View to ensuring the ignition of the carburetted mixture passing out of this divergent.
Other objects and advantages of the invention will appear to those skilled in the art from the following detailed description. There will now be described, by way of illustration of the possibilities of the lapplication of the invention, two forms of embodiment given by way of example without implied limitation, and shown in the accompanying diagram-matic drawings, in which:
FIG. l shows in elevation, partly in section, a spraying device in accordance with the invention.
FIG. 2 is an enlarged horizontal section of the liquid injector of the device .shown in FIG. 1, and
FIG. 3 is a longitudinal section of a burner embodying the invention.
A spraying device for mines in laccordance with the invention comprises essentially: an open casing 1 in which is arranged a convergent-divergent discharge-nozzle 2 extended by a divergent portion 3. Around the dischargenozzle 2, a casing 4 is xed by a nut 3a so as to surround the discharge-nozzle 2 by an -annular chamber 5, which is supplied with compressed air through a piping system 6 (screwed into the casing 4) on which is screwed a coupling 7 terminated by a valve 8, the coupling 7 receiving the compressed air from a supply tube (not shown) which is screwed into the internally threaded end 9.
The chamber discharges into the interior of the discharge nozzle 2 through an annular slot 10 formed between the upstream extremity 11 of the discharge-nozzle 2 and a member 12 which forms the front portion of the convergent-divergent unit 12, 2, 3 and being arranged in the front portion of the casing `4, said member 12 being screwed inside the front portion of casing 4. By construction, the extremity 11 is such that it torms an extended lip of the slot which continually recedes from the outlet direction 13 (in broken lines) of the slot 10, in the plane of FIG. 1.
In the immediate vicinity of the slot '10 is arranged the end orifice 14 of an injector 1S which receives liquid to be sprayed from a conduit system (not shown) through the intermediary of a coupling 16 provided with a valve 17.
The injector 15, which is shown -to a larger scale and in a longitudinal section in lFIG. 2, comprises a threaded tube 18 on which is screwed, on the one hand, the threaded end 19 of the coupling (see FIG. 1), and, on the other hand, a conical hood 20 in which is formed the end orice 14. A clip 21 is provided to retain the hood 20` in its cor-rect position, as explained below.
The bore 22 of the -tube 18 communicates by means of holes 23 formed in the reduced end portion 24 of this tube, with a `chamber 25a which is provided between the hood 20 and the tube 18. The end of the tube `18 has, in longitudinal section, the shape of `an arrow-head 26 so as to form a peripheral narrowed portion or slot at 27 between the chamber 25a and a chamber 25b. The thickness of the peripheral narrowed portion can be varied by screwing-in or out the hoo-d 20.
The operation of the `device sho-wn in FIGS. l and 2 is as follows:
By open-ing the valves 8 and 17, the chamber 5 is supplied With compressed air and liquid is supplied to the bore 22. The compressed air is discharged from the chamber 5 through the slot 10 and creates a pressure drop or reduced pressure in the vicinity of the slot, due to the above-mentioned `C-oanda elect, which results in a suction of fluid in the vicinity of the slot. There is produced in consequence a movement of air inside Ithe casing 1 in the direction of the arrows F and of liquid through the hole 14.
The liquid entering through the bore 22 passes through the holes 23 and is discharged through the adjustable slot 27 into the chamber 25h from which it passes out at 14. The particles of liquid passing out through the hole 14 are carried away with the a-ir arriving in the direction of the arrows F into the interior of the discharge nozzle 2 and of the extension 3. There is thus produced a tine atomization of liquid in the air (arrow IF). Finally, an extremely ne mist and/or an aerosol is discharged in the direction of the arrows F at the extremity 28 of the extension 3 which passes into the free air.
The means of regulation are as follows: action on the valve 8 to regulate the rate of ilow of compressed air; controlling the relative position of the members 12 and 2 by screwing or unscrewing the member 12 in the casing 4 thereby varying the width of the slot 10; regula-tion by the valve 17 to regulate the admission of liquid; action on the hood 20 to vary the slot 27, the extremity 21a of the clip 21 passing into one of the reference marks formed on the periphery of the hood 20.
The burner shown in FIG. 3 comprises an atornisation or spraying portion identical with that Shown in FIGS. 1 and 2, and the same reference numbers have been applied in FIG. 3 to the corresponding elements shown in FIGS. l and 2.
In FIG. 3, only the end of the hood of the injector can be seen, the injector is identical with that shown in FIG. 2. The convergent-divergent discharge-nozzle 2 is extended by a divergent portion 3' which is longer than the portion 3 of IFIG. 1, and is extended in its turn by a substantially cylindrical portion 30, in which there has been formed a series of orifices 31 which preferably have increasing diameters -in the direction of tlow of the iluids according to arrows F'. The port-ion 30 is surrounded by a casing 32 provided with at least `one spark plug 33 of the type used in internal combustion engines, and producing between its electrodes 34 at the level of the holes 31, a spark which ignites the carburetted mixture F which passes through the holes 31.
The adjustment of the burner is effected by means of the regulating elements described above in connection with the spraying device of FIGS. 1 and 2; regulation of the admission of air by the valve which controls this ow in the conduit 6; adjustment of the width of the slot 10 through which the chamber 5 discharges into the convergent of the discharge-nozzle 2; regulation of the quantity of liquid fuel arriving through the hole 14 by means of the liquid control admission valve and the screwing in or out of the hood 20.
It will of course be understood lto those skilled in the art that various improvements may be made tot the forms of construction above described and shown together with modications or additions, or replacement of certain members by corresponding members, without thereby departing from the scope of the present invention as determined by the appended claims.
What I claim is:
l.- A burner comprising in combination, a venturi nozzle having an inlet end, a convergent portion, a divergent portion downstream of the convergent portion and a discharge end, means deiining a chamber provided with a circular slot opening into the convergent portion of said venturi nozzle in the vicinity of the inlet end, means for delivering gas under pressure into said chamber to cause it to ow out of said slot, said slot having in an axial section through said nozzle an extended lip which continually recedes from the direction of emergence of said compressed gas through said circular slot, an atomizerinjector nozzle cooperative with the venturi nozzle spaced axially from the venturi nozzle and disposed eccentric to a longitudinal axis of said venturi nozzle and parallel to said axis for discharging a combustible iluid into the inlet end of said venturi nozzle in the immediate vicinity of the circular slot, said venturi nozzle having a plurality of peripheral axially spaced apertures of different areas forming orices of dii'erent sizes in the vicinity of said discharge end, means providing a chamber around the nozzle orifices forming a burner therewith, and ignition means in said chamber for igniting a combustible iluid discharged from the atomizer-injector nozzle, and means to supply a combustible liquid under pressure to said atomizer-injector nozzle, whereby said generator is usable as a burner.
2. An aerosol generator comprising in combination, a venturi nozzle having an inlet end, a convergent portion, a divergent portion downstream of the convergent portion and a discharge end, means defining a chamber provided with a circular slot opening into the convergent portion of said venturi nozzle in the vicinity of the inlet end, means for delivering gas under pressure into said chamber to cause it to ilow out of said slot, said slot having in an axial section through said nozzle an extended lip which continually recedes from the direction of emergence of said compressed gas through said circular slot, an atomizer-injector nozzle cooperative with the venturi nozzle spaced axially from the venturi nozzle and disposed eccentric to a longitudinal axis of said venturi nozzle and parallel to said axis for discharging a finely divided liquid into the inlet end of said venturi nozzle in the immediate vicnity of the circular slot, said atomizerinjector nozzle comprising a minute discharge orice positioned to discharge in the immediate vicinity of a limited portion of said slot, and means to supply a liquid under pressure to said atomiZer-injector nozzle,
3, An aerosol generator comprising in combination, a Venturi nozzle having an inlet end, a convergent portion, a divergent portion downstream of the convergent portion and a discharge end, means defining a chamber provided With a circular slot opening into the convergent portion of said venturi nozzle in the vicinity of the inlet end, means for delivering gas under pressure into said chamber to cause it to llow out of said slot, said slot having in an axial section through said nozzle an extended lip which continually recedes from the direction of emergence of said compressed gas through said circular slot, an atomizer-injector nozzle cooperative with said venturi nozzle spaced axially from the venturi nozzle and disposed eccentric to a longitudinal axis of said venturi nozzle and parallel to said axis for discharging into the inlet end of said venturi nozzle in the immediate vicinity of the circular slot, said atomizer-injector nozzle being disposed eccentric to a point corresponding to a center for said slot, and means to supply a liquid under pressure to said atomizer-injector nozzle.
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